Detroit I could see, as it was a central hub in the past, and much of that infrastructure still stands. Plus, given the problems they've had, property is really cheap, while still having access to the amenities of a city.
"People" also have to want to live there. And by "people" I mean there has to be at least some sort of general appeal of the location to a large portion of the population. Despite everyone's whining about the government or how obnoxious its residents are, California is a pretty great place to be, and was that way 40 years ago as well. Detroit has a pretty major stigma to overcome, and I doubt it could when there are plenty of other places with similar advantages and no stigma.
Agreed, the biggest thing is that people have to want to be there. Some of these places are getting a little of the SV success due mainly to generally being a desirable place to be, and getting a little push from the local government.